I would like to ask a question on HVAC modeling of winter vs summer operation. I am working with an all-air system. I have to build a network that works differently in summer and winter. In particular, there are different temperatures and humidities that are involved in the operation. For summer, there is a cooling battery that works first, then a heating battery to bring the air to the desired temperature and humidity. In this case, there is a de-humidification involved in the process. The transformations that the air undergoes are written in the following scheme, for summer:
28,1°C temperature; 74% relative humidity ----> 13,5°C; 100% ----> 20°C; circa 60%
For winter, the air undergoes humidification, there is a heating battery working first, then a humidifier, then another heating battery to bring the air to the desired temperature and humidity:
16,9°C temperature ----> 28°C; 6% relative humidity ----> 13°C; 79% ----> 26,5°C; circa 40%
To simulate these 2 different operations, we imagined having two branches of the network, one working for summer and one working for winter. The flow is controlled by a percentage flow sensor that is connected by an AND to a temperature sensor after the room; if the temperature sensor detects a T=20°C (winter setpoint) it means we are in winter, so the flow will be all diverted (100% in the percentage flow sensor) to the upper branch of the network. I will attach an image of how we imagined the system to be modeled:
Unfortunately, there is an error occurring when the simulation starts. "Flow at node 1/ cannot be set - insufficient control definition". Node 1 is the one entering the heat exchanger, after the green arrow.
Does anyone know how can I solve this problem? It would be very helpful for me. If you need any further information, I am here to give them.